Abstract : The report considers the ESNA tri-colored cover on a 250mm lantern as a possible solution to meet requirements for a single station range light. The main consideration is the ability of the plastic cover to present clearly defined colored sectors to moving observers operating in the far field of the range light. Usually the design trend is to attempt to approach as closely as possible an instantaneous color change between sectors as the observer changes azimuth. Tests were conducted to measure the intensity and color as a function of observer azimuth from the range light. The results of these tests were compared with the performance of actual observers to include physiological phenomena. These results then allow qualitative results to be assigned to overall physiological performance concerning color determination under the given test conditions. The sector alignment variation as a function of lamp changer position was investigated. Effects of intensity inequalities in the three sectors caused by the low transmittance of the red and green colored sectors as compared with the clear central sector were investigated. These tests compared results by observers reporting on the unequal intensity sectors and approximately equal intensity sectors obtained by the use of neutral density filters. The results of both conditions were very close with no significant differences uncovered. It was found that based on laboratory tests the ESNA tri-colored cover should be an acceptable solution to the single station range light problem. (Author)